1. Field of the Invention
The present invention relates to an apparatus for measuring the seat weight including the weight of a passenger seated on the car seat and, more specifically, to a seat weight measuring apparatus having advantages including that the production cost and the assembling cost of such apparatuses may be reduced.
2. Description of the Related Art
Automotive vehicles are equipped with seat belts and air bags as equipment for ensuring the safety of the passenger. In recent years, an effort has been underway to enhance the performance of the seat belt and/or the air bag by controlling these devices in accordance with the weight or the posture of the passenger. For example, the quantity of gas used to deploy the air bag or the speed of deployment could be controlled. Further, the amount of pretension of the seat belt could be adjusted in accordance with the weight and posture of the passenger. To this end, it is necessary to know the weight of the passenger sitting on the seat by some technique. The position of the center of gravity of the passenger sitting on the seat could also be referenced in order to estimate the posture of the passenger.
As an example of a technique to determine the weight or the center of gravity of the passenger of this type, a method of measuring the seat weight including the passenger""s weight by disposing the load sensors (load cells) at the front, rear, left and right corners under the seat and summing vertical loads applied to the load cells has been proposed in Japanese Unexamined Patent Application Publication No. H11-304579, the disclosure of which is hereby incorporated by reference. Through this proposed method, the position of the center of gravity of the passenger sitting on the seat can be known.
Since a seat weight measuring apparatus of this type is intended for use in general automotive vehicles, the cost of the apparatus must be as low as possible. In addition, the wiring and assembly also must be easy. Keeping such subjects in mind, the object of the present invention is to provide a seat weight measuring apparatus having such advantages that the production cost and the assembling cost may be reduced.
Accordingly, a first embodiment of the present invention is a seat weight measuring apparatus for measuring the weight of the passenger sitting on the seat applied to the seat wherein a load sensor is installed at one location where the seat is fixed to the vehicle body, for measuring a part of the load applied to the seat including the seat back and the sitting surface of the seat.
According to this embodiment of the invention, because a load sensor is installed only at a single location of the seat, the production cost and the assembling/wiring cost may be reduced in comparison with the related art.
The object of the seat weight measuring apparatus stated in this specification is basically to measure the weight of the passenger sitting on the seat. Therefore, the apparatus for measuring only the weight of the passenger by canceling the net weight of the seat is included in the seat weight measuring apparatus stated in this specification.
The seat weight measuring apparatus according to a second embodiment of the present invention is a seat weight measuring apparatus for measuring the weight of the passenger sitting on the seat applied to the seat, further comprising a load sensor installed at one of the left and right seat frames at a portion of the seat at which the seat is fixed to the vehicle body, and a restraining mechanism for restraining a part of force applied to said load sensor within said seat frame. Because the impact or the like applied to the load sensor is restrained by the restraining mechanism, the load sensor is prevented from being damaged.
The seat weight measuring apparatus of the present invention may further comprise a position sensor for detecting the position of said passenger on the seat. Taking the result detected by the position sensor makes the result detected by the load sensor more accurate.
Another embodiment of the invention is a seat weight measuring apparatus wherein a load sensor is installed on the seat frame on which the buckle of the seat belt is fixed in order to reduce the effect of the restraint of the passenger by the seat belt on the detection of the load.
Another embodiment of the present invention is a seat weight measuring apparatus wherein the restraining mechanism selectively transmits only the load in the vertical direction with respect to the car body to the load sensor.
Another embodiment of the present invention is a seat weight measuring apparatus wherein the restraining mechanism includes a displacing mechanism so that a load applied to the load sensor by the impact applied to the seat or the deformation of the seat is mechanically restrained.
Another embodiment of the present invention is a seat weight measuring apparatus wherein a load sensor for measuring the load applied to the seat frame and a restraining mechanism are installed between the frame of the seat rail and the seat mounting portion to be attached to the vehicle body.
Another embodiment of the present invention is a seat weight measuring apparatus wherein a load sensor for measuring the load applied to the seat frame and a restraining mechanism are installed between the slide frame of the seat rail and the seat frame comprising a seat pan and seat back joined together.